[System Health] Change scrolling behaviour for news sites.

tools/perf/page_sets/system_health/browsing_stories.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from page_sets.system_health import platforms
 from page_sets.system_health import system_health_story
 
 from page_sets.login_helpers import pinterest_login
 
 from telemetry import decorators
@@ skipping 58 matching lines @@
 
   def _DidLoadDocument(self, action_runner):
     for i in xrange(self.ITEMS_TO_VISIT):
       self._NavigateToItem(action_runner, i)
       self._ReadNewsItem(action_runner)
       self._NavigateBack(action_runner)
       self._ScrollMainPage(action_runner)
 
   def _ReadNewsItem(self, action_runner):
     action_runner.tab.WaitForDocumentReadyStateToBeComplete()
-    action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS)
+    action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS/2)

[rnephew (Reviews Here), 2016/11/15 22:08:43]

We could also have it wait the entire time before and after, but that will
increase the run time of the SH tests; but assuming my reason why we didn't
catch it is correct it would increase the likelihood of us catching it..

[perezju, 2016/11/16 09:58:05]

Note: This is doing integer division. So before it was waiting 3 seconds in
total, it now waits 2 * (3 / 2) = 2 * 1 = 2 seconds!

I think what you want is:

  action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS / 2.0)

     action_runner.RepeatableBrowserDrivenScroll(
         repeat_count=self.ITEM_SCROLL_REPEAT)
+    action_runner.Wait(self.ITEM_READ_TIME_IN_SECONDS/2)
 
   def _ScrollMainPage(self, action_runner):
     action_runner.tab.WaitForDocumentReadyStateToBeComplete()
     action_runner.RepeatableBrowserDrivenScroll(
         repeat_count=self.MAIN_PAGE_SCROLL_REPEAT)
 
 
 # TODO(ulan): Enable this story on mobile once it uses less memory and does not
 # crash with OOM.
 @decorators.Disabled('android',
@@ skipping 273 matching lines @@
       inner_save_function = 'document.querySelector(".nameAndIcons")'
       action_runner.WaitForElement(element_function=inner_save_function)
       action_runner.ClickElement(element_function=inner_save_function)
       action_runner.Wait(1)  # Wait to make navigation realistic.
 
     # Close selection.
     x_element_function = ('document.querySelector('
                           '".Button.borderless.close.visible")')
     action_runner.ClickElement(element_function=x_element_function)
     action_runner.Wait(1)  # Wait to make navigation realistic.